This patch addresses an issue with buggy userspace code sending I/Ovia scsi-generic that does not explictly clear their associated readbuffers. It adds an explict memset of the first SGL entry withintcm_loop_new_cmd_map() for SCF_SCSI_CONTROL_SG_IO_CDB payloads thatare currently guaranteed to be a single SGL by target-core code.

This issue is a side effect of the v3.1-rc1 merge to remove theextra memcpy between certain control CDB types using a contigious+ cleared buffer in target-core, and performing a memcpy into theSGL list within tcm_loop.